Saturday, January 28, 2012

Body Organs and Systems Related to Behavior

NERVOUS SYSTEM: THE BIOLOGICAL CONTROL CENTER

The complex mass of nerve cells called the brain not only thinks and calculates but also feels and controls actions.

Neurons: The Units of the Nervous system

The most important unit of the nervous system is the individual nerve cell, or neuron

Parts of Neurons

Neurons range in length from less than a millimeter to more than a meter in length. The parts are: the Cell body, Dendrites and Axons.

A nerve is a bundle of many long neurons – sometimes thousands of them – outside the brain and spinal cord.

Neural Transmission

Neurons are the “wires’ of the nervous system-messages are transmitted over the neuron much like your voice is transmitted over a telephone line. But neurons have their own built-in supplies of electrical power – they are the “batteries” of the nervous system, too.

Synaptic Transmission

Neurons are not directly connected to each other. The junction between one neuron and another is called the synapse

DIVISIONS OF THE NERVOUS SYSTEM

The major divisions of the nervous system are the central nervous system and the peripheral nervous system.

Divisions of the Peripheral Nervous System

The PNS is further divided into the somatic and autonomic nervous systems. The SNS carries messages from the central nervous system to the muscles of the skeleton that controls movements of the body.

The ANS is composed of nerves that carry messages to and from the glands and visceral organs (heart, stomach, intestines, etc.).

Divisions of theautonomic Nervous Systems

The ANS can itself be divided into sympathetic division and parasympathetic division.

STRUCTURE AND FUNCTIONS OF THE BRAIN

The brain is the fundamental basis for psychological life.

1. Hindbrain and Midbrain: Housekeeping Chores and Reflexes

The hindbrain is the lowest part of the brain, located at the rear base of the skull. Its primary responsibility is to perform routine “housekeeping” functions that keep the body working properly.

The midbrain is a small area at the top of the hindbrain that serves primarily as a center for several postural reflexes, particularly those associated with the senses.

2.Forebrain: Cognition, Motivation, emotion and Action

Structurally, the forebrain consists of two distinct areas. One area, which contains the thalamus, hypothalamus, and most of the limbic system, rests at the top of the hindbrain and midbrain

3. Thalamus, Hypothalamus, and Limbic System

The thalamus is a switching station for messages going to and from the brain.

Limbic system is a complex neural system composed of several parts. The amygdala appears to play strong part in activating the emotions of fear and rage.

The hippocampus is important in the regulation of emotion and is also involved in the formation of new memories.The memory loss experienced by patients suffering from Alzheimer’s disease results in part from damage to the hippocampus.

4.Cerebral cortex, Sensory, cognitive and Motor functions

The largest structure in the forebrain is called the cerebral cortex. It is involved in the conscious experience, voluntary actions, language, and intelligence. – many of the things that make us human.

5. Lobes of the Cerebral Cortex

Frontal Lobes

Parietal Lobes

Temporal Lobes

Occipital Lobes

6.Hemisphere of the Cerebral Cortex

If we look down at the cerebral cortex from the top, however, we can see that it also is made up of two halves called the cerebral hemispheres. Input from the senses of vision and touch, goes to the opposite hemisphere. Stimulation of the skin on the left hand goes to the right cerebral hemisphere.

7. Hemispheres of the Cerebral Cortex and Emotion

The right hemisphere appears to be more involved with processing of negative emotions, where as the left hemisphere plays a greater role in the processing of positive emotions.

8. The brain is an interaction system

In terms of computer jargon, the brain often uses parallel processing rather than serial processing. The brain’s amazing capacity for parallel processing magnifies its ability to use its 100 billion neurons and their trillions of connections to produce our complexactions, emotions, and thoughts.